Conventionally, high-power batteries are mounted in electric cars including motors as their driving sources and hybrid cars including motors and engines as their driving sources. Flat thin secondary cells are used for single cells in the high-power batteries. Stacking to electrically connect the single cells in series or in parallel forms a high capacity battery module. Further, combining to electrically connect the battery modules forms an assembled battery, which is mounted in an automobile. Including flat single cells, each battery module can be formed into a compact, high-energy density battery module.
Laminate type batteries are used as the thin single cells, each of which has a configuration that an electric power generation element, which includes a flat positive electrode plate, a flat negative electrode plate and a separator disposed therebetween, is sealed with an exterior package such as a laminated film, where the rim of the battery is thermal welded to seal the electric power generation element and an electrolytic solution therein, and electrode tabs connected to the positive electrode plate and the negative electrode plate are drawn to the outside from end portions of the battery.
The voltage of each laminate type battery in the battery module including the stacked laminate type batteries changes with the condition change of the moving automobile. To keep observing the state of charge and discharge of the laminate type batteries by precisely grasping the voltage of each laminate type battery is important in order to improve the reliability of the automobile. For this purpose, voltage detecting terminals arranged to measure voltage are each provided to the laminate type batteries.
It is known that connector terminals are used to connect the voltage detecting terminals provided to the laminate type batteries with an external device.
It is known that in order to detect the voltage of each of the laminate type batteries in the battery module, instead of connecting voltage detecting harnesses with the electrode tabs of the laminate type batteries, the voltage detecting terminals are firstly connected with the laminate type batteries, connectors with which voltage detecting harnesses are connected are connected with the voltage detecting terminals after the single cells with the voltage detecting terminals are stacked, and then the voltage detecting terminals are connected with the voltage detecting harnesses by one operation (see PTL 1, for example).